Carafe filter with air lock prevention feature

ABSTRACT

A filter for gravity-fed applications, having filter media with a hollow center, the filter being generally prone to a degradation or cessation in fluid flow due to air entrapment or air lock within the filter housing cavity, which develops during filtering. A diffuser element is introduced to pierce the entrapped air bubble, the diffuser element being an elongated structure connected to the filter housing top end cap and extending through the entrapped air bubble to the filter media.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a filter, specifically, a filter thatis designed for gravity-fed applications, having filter media withhollow center, the filter being generally prone to a degradation orcessation in fluid flow due to air entrapment or air lock within thefilter housing cavity, which develops during filtering. A diffuserelement or surface tension disrupter is introduced to the filter housingin order to pierce the entrapped air bubble, and prevent air lock fromoccurring during filtering by dispersing an otherwise large air bubbleblockage, and allowing fluid to flow through the smaller entrapped airbubbles.

2. Description of Related Art

The presence of unwanted and potentially harmful contaminants indrinking water is a cause for health concern. This concern causes adesire for water treatment devices suitable for use in the home and asportable instruments for water treatment. Several types of gravity-flowfiltration systems have been developed to address various healthconcerns.

A common application of the instant invention is directed to a batchtreatment and filtration device where water is filtered, treated, andstored in a container. The treated water is poured from a spigot of thewater container which functions as a self-contained water treatmentsystem. These self-contained systems typically have upper and lowerchambers separated by a filter cartridge. The most popular styles beingthe pour-through carafe or the refrigerator water tank. Such systemsinclude an upper reservoir for receiving unfiltered water, a lowerreservoir for receiving and storing filtered water, and a filter,usually of granular activated carbon or pleated fiber sheets, with atleast one inlet at the filter housing top and at least one outlet at thefilter housing bottom, which allows water to flow from the upperreservoir to the lower reservoir. The pour-through carafe is sized to behandheld, holds about one-half gallon of water, and may be tipped forpouring filtered water, as in a conventional pitcher or carafe.

Gravity flow carafe filters have been commercially available for severalyears and their popularity with consumers continues to grow. Currentlyavailable commercial water carafes are capable of removing lead using anion exchange resin, undesirable tastes and odors using carbon granules,and large particles using a packed bed configuration.

The refrigerator tank system is typically a larger rectangular tank witha spigot for draining filtered water into a glass or pan. Both thecarafe or tank designs use gravity to cause the unfiltered water in thetop reservoir to flow down through the filter cartridge and into thelower reservoir where the filtered water remains until it is used.

Filter media used for these types of applications is generallycylindrical in shape with a hollow center for fluid flow. Theintroduction of the unfiltered fluid through the filter media is knownto entrap air between the hollow center and the housing top cap, forminga large air bubble. This air bubble prevents fluid from entering thecore and displacing the air, resulting in what may be generally referredto as a “vapor lock” or “air lock” condition, which degrades or ceasesfluid flow.

In the prior art, care is taken to maintain a fully primed condition,i.e., preventing air access to the primed filter. Allowing air accessallows blocking air inclusions removed during priming to re-form in thefilter pore structure, significantly reducing flow until the primedcondition is re-established. The advantage of maintaining the primeextends to essentially any micro-porous filter medium regardless ofcomposition, including ceramic, carbon, or polymer membranes or filterbodies of inorganic or organic composition. However, this techniquerequires the filter media to remain constantly and completely submergedin water, so that air inclusions in the filter cannot re-form.

The present invention is designed to mitigate air lock upon introductionof unfiltered water into the filter media even when not fully submerged.

SUMMARY OF THE INVENTION

Bearing in mind the problems and deficiencies of the prior art, it istherefore an object of the present invention to provide a gravity-fedfiltration system capable of maintaining fluid flow even when entrappedair within the hollow center of the filter media is introduced duringfiltration.

The above and other objects, which will be apparent to those skilled inthe art, are achieved in the present invention which is directed to afilter for gravity-fed applications comprising: a top cap having fluidingress apertures and in fluid communication with a filter media; thefilter media having a hollow center; a bottom cap attached to the filtermedia; and a diffuser extending from the top cap to the filter mediahollow center; wherein the top cap is substantially submerged by fluidduring filtration, and the diffuser pierces any air bubble formed in thehollow center during the filtration.

The filtration includes submerging at least the top cap of the filter influid under gravity, and having the fluid enter the filter media throughthe hollow center, and traverse radially outwards through sidewalls ofthe filter media, or traverse axially downwards through the bottom cap,or both.

The diffuser may comprise an elongated cylindrical extension and mayinclude a tapering sidewall.

The diffuser may extend within at least a top portion of the hollowcenter of the filter media, and may be integral with the top cap.

In a second aspect, the present invention is directed to a filterhousing for gravity-fed applications including: a top end cap havingapertures for fluid ingress; a housing body attached to the top end cap;a filter media having a hollow center and encased by the housing body; abottom end cap attached to the housing body; apertures for fluid egresslocated through the housing body or the bottom end cap or both; and anairlock prevention probe attached to the top end cap, the airlockprevention probe extending from the top end cap to a point adjacent atopmost portion of filter media encased in the housing body.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention believed to be novel and the elementscharacteristic of the invention are set forth with particularity in theappended claims. The figures are for illustration purposes only and arenot drawn to scale. The invention itself, however, both as toorganization and method of operation, may best be understood byreference to the detailed description which follows taken in conjunctionwith the accompanying drawings in which:

FIG. 1 depicts a side view of a filter housing that employs the air lockprevention feature of the present invention;

FIG. 2 depicts a cross-sectional view of the filter housing of FIG. 1;

FIG. 3 depicts a top perspective view of the filter housing of FIG. 1;

FIG. 4 depicts a top perspective, exploded view of the filter housingwith a sidewall; and

FIG. 5 depicts a top perspective, exploded view of the filter housingwithout a sidewall.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

In describing the preferred embodiment of the present invention,reference will be made herein to FIGS. 1-5 of the drawings in which likenumerals refer to like features of the invention.

FIG. 1 depicts a side view of a filter housing 10 that may be used toemploy the novel air lock prevention feature of the present invention.Like most filter housings, filter housing 10 includes a top cap 12circumferentially secured or attached to a filter media top end cap 15,which attaches to filter media 22. Filter media top end cap 15 isgenerally fixed to filter media 22 by a sealant or friction fit. Filtermedia 22 is shown as pleated fiber sheets, but may also be a carbonblock or other suitable media having a hollow center. As a pleatedlayered material, filter media 22 may also include a pleat pack, anouter fiber sheet, and a drainage layer. Other layered combinations arenot excluded, and the present invention will work well with any filtermedia having a hollow center.

The filter may further include a side housing shell or outer shroud 14.The filter media is terminated circumferentially to a bottom cap 16. Inthis embodiment, the filter side housing shell has side apertures 18 onshroud 14, which allow for filtered fluid to flow out of filter housing10; however, side housing apertures 18 need not be configured or shapedas shown, and any aperture configuration that allows for continuousfiltered fluid flow into a retaining basin would be sufficient. For agravity-fed filtration system it is only necessary that an egressaperture be available for filtered water to flow into the retainingbasin or storage container (not shown). Such designs normally employ abottom egress point at bottom cap 16, which could be utilized in thepresent invention without adverse performance, or side housing aperturesas shown.

The present invention is designed to accommodate filter media wherefluid permeates radially through the media and may exit the sidewalls orthe bottom cap. This directional flow generally causes air to build-upin the hollow center of the filter media. The entrapped air may causevapor lock, which ultimately degrades or substantially ceases fluidflow.

FIG. 2 depicts a cross-sectional view of filter housing 10 of thepresent invention. Hollow center 20 centers filter media 22 about anaxial center of cylindrical filter 10. In this embodiment, filter media22 comprises pleated fiber sheets; however, the filter media may also bea solid block media, such as an extruded cylindrical, carbon block. Thefilter housing is designed so that fluid flows from ingress ports on topcap 12 and filter media top end cap 15 through hollow center 20 offilter media 22, and radially outwards towards side apertures 18. Fluidmay also flow outwards through the periphery of bottom cap 16 afterhaving traversed through filter media 22.

Generally, an air pocket or bubble 24 located at the top of filter media22 will entrap air within hollow center 20 during filtration, andadversely affect fluid flow into hollow center 20. Essentially, duringfiltration top cap 12 is submersed in fluid, and air is not easily ableto escape the filter. To mitigate this air entrapment, top cap 12includes an elongated surface tension disrupter or diffuser 26 extendingfrom top cap 12 adjacent to, or extending within, hollow center 20, andspecifically designed to pierce air pocket 24, preferably terminatingjust below the topmost portion of filter media 22. Diffuser 26 ispreferably shaped in a needle-nose or pin-like fashion capable ofpiercing air pocket 24, and breaking up the surface tension that holdsand forms air pocket 24 into smaller air bubbles that are not capable ofretaining a vapor lock. In this manner, any air buildup at air pocket 24which is formed as a consequence of fluid ingress will no longeradversely affect the fluid flow since the surface tension of the airpocket is destroyed by the surface tension disrupter or diffuser 26.

Diffuser 26 may be a shape other than a needle-nose or pin-likeextension. For example, it may be an elongated cylindrical extension, orthe like, that by design protrudes into and through a potential airbubble of predetermined size within hollow center 20, and extends withinthe topmost portion of the filter media. The length of diffuser 26 issuch that it is capable of extending within hollow center 20 to piercean air bubble of predetermined size.

As depicted in the drawings, diffuser 26 is shown preferably shaped as aneedle-nose tube, having a generally cylindrical cross-section with atapering endpoint at the junction of filter media 22. However, thepresent invention is not limited to any particular cross-sectional shapefor the diffuser provided that the selected shape allows the diffuser topierce the air bubble that forms during fluid flow.

FIG. 3 depicts a top perspective view of the filter housing of thepresent invention. Top cap 12 is depicted with several water ingressports or apertures 30 a-c. Apertures 30 a-c allow fluid to flow intofilter 10 when the filter top cap 12 is partially, or more likely,completely submerged in fluid. Fluid enters through these apertures andis directed to the hollow center 20 of filter media 22. Fluid isdirected to the side walls of filter media 22, traversing radiallyoutwards from hollow center 20.

FIG. 4 depicts a top perspective, exploded view of the filter housing 10with a sidewall 14. Sidewall 14 may or may not include apertures. Ifsidewall 14 does not include apertures, bottom cap 16 would provideapertures for fluid egress. In the embodiment depicted by FIG. 4,sidewall 14 is shown with apertures 18 for fluid egress.

As noted previously, filter media 22 is depicted as a set of pleatedsheets; however, it is also possible to use a solid cylindrical filtercore, such as a carbon block core, alone or in tandem with a pleatedfilter media.

FIG. 5 depicts a top perspective, exploded view of the filter housing 10without a sidewall. Fluid enters hollow center 20 and exits radiallythrough the sides of filter media 22. Also depicted in FIG. 5 arealignment tabs 32 to help secure top cap 12 with diffuser 26 to filtermedia end cap 15.

The present invention is not limited to the application of a singlefilter media, or of a filter media consisting solely of pleated sheets.As long as a center core is prone to entrapping air during filtration, adiffuser employed to pierce any air bubble formed during fluid flowwould sufficiently mitigate against an air lock condition that wouldotherwise develop whenever the fluid flow ingress exceeds the air flowegress.

While the present invention has been particularly described, inconjunction with a specific preferred embodiment, it is evident thatmany alternatives, modifications and variations will be apparent tothose skilled in the art in light of the foregoing description. It istherefore contemplated that the appended claims will embrace any suchalternatives, modifications and variations as falling within the truescope and spirit of the present invention.

Thus, having described the invention, what is claimed is:
 1. A filterfor gravity-fed applications comprising: a top cap having fluid ingressapertures and in fluid communication with a filter media; said filtermedia having a top end, a bottom end, and a hollow center; a filtermedia top end cap attached to said filter media at said top end, saidfilter media top end cap in fluid communication with said top cap; abottom cap attached to said filter media at said bottom end; and adiffuser extending from said top cap to said filter media hollow centerthrough said filter media top end cap, and within a top portion of saidfilter media hollow center; wherein said top cap is substantiallysubmerged by fluid during filtration, and said diffuser pierces any airbubble formed in said hollow center during said filtration.
 2. Thefilter of claim 1 wherein said filtration includes submerging at leastsaid top cap of said filter in fluid under gravity, and having saidfluid enter said filter media through said hollow center, and traverseradially outwards through sidewalls of said filter media, or traverseaxially downwards through said the bottom cap, or both.
 3. The filter ofclaim 1 wherein said diffuser comprises an elongated cylindricalextension.
 4. The filter of claim 3 wherein said diffuser includes atapering sidewall.
 5. The filter of claim 1 wherein said diffuser isshaped in a needle-nose or pin-like fashion capable of piercing airpocket within said top portion of said filter media hollow center. 6.The filter of claim 1 wherein said diffuser is integral with said topcap.
 7. The filter of claim 1 wherein said filter media includes pleatedfiber sheets formed with a hollow center.
 8. The filter of claim 1wherein said filter media includes a porous block formed with a hollowcenter.
 9. A filter for gravity-fed applications comprising: a top caphaving fluid ingress apertures and in fluid communication with a filtermedia; said filter media having a hollow center; a bottom cap attachedto said filter media; and a diffuser extending from said top cap to saidfilter media hollow center and within a top portion of said filter mediahollow center; a filter media top end cap such that said filter media isattached to said filter media top end cap at a top end, and said bottomcap at a bottom end; and said filter media top end cap attached to, andin fluid communication with, said top cap; wherein said top cap issubstantially submerged by fluid during filtration, and said diffuserpierces any air bubble formed in said hollow center during saidfiltration.
 10. The filter of claim 9 including a sidewall housing shellencompassing said filter media, said sidewall housing shell attached tosaid filter media top end cap and said bottom cap.
 11. The filter ofclaim 10 wherein said sidewall housing shell includes apertures forfluid egress.